With rapid development of mobile communications technologies and improvement of hardware system performance, users also have increasing requirements on file storage. An existing USB flash drive or optical disc can no longer meet storage requirements. A hard disk is usually used as a storage medium, and in addition, it is required that the hard disk is inserted and removed conveniently, so that a common home terminal user can replace the hard disk very conveniently. However, the hard disk cannot be inserted or removed with power on, and the hard disk cannot be removed randomly when running at a high speed. Otherwise, the hard disk may be damaged, which causes a user information loss. To prevent the hard disk from being damaged because the common home terminal user randomly inserts or removes the hard disk, a defense apparatus needs to be designed.